Cole vs The Other Ninja (power ups)

Having binged watched Ninjago up to the third season of Dragons Rising, why does it seem like Cole is the only one to gain any permanent power ups? At the end of Day of the Departed, he gains his "Lava Arms" power up. We don't see any of the other ninja gain anything similar to it. Nya becomes one with the sea but that was a sacrifice play and ended up being temporary. Zane becomes the Ice Emperor but that was due to the Scroll of Forbidden Spinjitzu and manipulated by Vex. Otherwise, any...